Isolated hole detection and growth

ABSTRACT

The present disclosure relates to a method and system for processing isolated holes in an image to be printed or displayed. The method includes generating a random number lying in a finite range of numbers, determining whether a target pixel is to be turned off and enabled for printing as a hole, determining a sum of pixels surrounding a target pixel in a plurality of pixels in a scanline of the image, the target pixel corresponding to an isolated hole in an input image, that are in an on state, the on state defined by a higher binary logic level relative to a binary logic level corresponding to a turned off pixel, determining a numerical value stored in a lookup table in a memory unit coupled to the processor using the determined number of pixels that are in the turned on state surrounding the target pixel.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to U.S. patent application entitled “DOTGROWTH SYSTEM AND METHOD,” Ser. No. 13/547,765, “DOT GROWTH SYSTEM ANDMETHOD,” Ser. No. 13/547,802, “ISOLATED HOLE DETECTION AND GROWTH,” Ser.No. 13/547,839, “METHOD AND SYSTEM FOR ISOLATED HOLE DETECTION ANDGROWTH IN A DOCUMENT IMAGE,” Ser. No. 13/547,670, “METHOD AND SYSTEM FORISOLATED DOT DETECTION AND GROWTH IN A DOCUMENT IMAGE,” Ser. No.13/547,738, all filed concurrently with the present application, and allincorporated by reference herein in their entireties.

FIELD

The present application relates to a method and system for processingholes of an image for displaying and/or printing.

BACKGROUND

One common problem seen on xerographic marking engines is the inabilityto consistently or uniformly print small, isolated dots, for example, inbinary bitmaps of an image. This causes image quality defects such asmissing highlight tone and dotted lines. The same problem exists at theother end of the spectrum. Often in very high density regions, isolatedholes cannot be reproduced by marking engines due to dot size or gain,making gray levels indistinguishable. To deal with marking engines ofdifferent characteristics, finer control of density adjustment is neededthat can avoid inconsistent outputting of a single isolated dot or holein an output image. Inconsistent and non-uniform isolated small dots orholes are hard to avoid resulting in artifacts in an output image.

SUMMARY

To achieve the desired growth behavior, one aspect of the presentapplication provides a method for selectively processing isolated holesof an image to be printed by a printing device. The method includesgenerating at a processor a random number lying in a finite range ofnumbers. Whether a target pixel is to be turned off and enabled forprinting as a hole is determined. A sum of pixels surrounding a targetpixel in a plurality of pixels in a scanline of the image is determined,the target pixel corresponding to an isolated hole in an input image,that are in an on state, the on state defined by a higher binary logiclevel relative to a binary logic level corresponding to a turned offpixel. A numerical value stored in a lookup table in a memory unitcoupled to the processor is determined using the determined number ofpixels that are in the turned on state surrounding the target pixel. Thegenerated random number is compared to the determined numerical value.Whether the target pixel enabled for holegrowth is to be enabled forholegrowth is determined based upon the comparing.

Another aspect of the present application provides a system forselectively processing isolated holes of an image to be printed by aprinting device. The system includes one or more processors. The one ormore processors are configured to generate a random number lying in afinite range of numbers, determine whether a target pixel is to beturned off and enabled for printing as a hole, determine a sum of pixelssurrounding a target pixel in a plurality of pixels in a scanline of theimage, the target pixel corresponding to an isolated hole in an inputimage, that are in an on state, the on state defined by a higher binarylogic level relative to a binary logic level corresponding to a turnedoff pixel, determine a numerical value stored in a lookup table in amemory unit coupled to the processor using the determined number ofpixels that are in the turned on state surrounding the target pixel,compare the generated random number to the determined numerical value,and determine whether the target pixel enabled for holegrowth is to beenabled for holegrowth based upon the comparison.

Yet another aspect of the present application provides a computerreadable medium having stored thereon instructions for selectivelyprocessing isolated holes of an image to be printed by a printingdevice. The machine executable code when executed by at least oneprocessor causes the processor to generate a random number lying in afinite range of numbers, determine whether a target pixel is to beturned off and enabled for printing as a hole, determine a sum of pixelssurrounding a target pixel in a plurality of pixels in a scanline of theimage, the target pixel corresponding to an isolated hole in an inputimage, that are in an on state, the on state defined by a higher binarylogic level relative to a binary logic level corresponding to a turnedoff pixel, determine a numerical value stored in a lookup table in amemory unit coupled to the processor using the determined number ofpixels that are in the turned on state surrounding the target pixel,compare the generated random number to the determined numerical value,and determine whether the target pixel enabled for holegrowth is to beenabled for holegrowth based upon the comparison.

Other objects, features, and advantages of the present disclosedtechnology will become apparent from the foregoing detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will now be disclosed, by way of example only, withreference to the accompanying schematic drawings in which correspondingreference symbols indicate corresponding parts, in which:

FIG. 1 illustrates a block diagram of a system for processing an inputdigital image for hole growth, according to an aspect of the presentdisclosure;

FIG. 2A illustrates a context window, according to an aspect of thepresent disclosure;

FIG. 2B illustrates an example set of patterns or templates for isolatedhole detection, according to an aspect of the present disclosure;

FIG. 3 illustrates of a flowchart of method for density control basedisolated hole growth, according to an aspect of the present disclosure;

FIG. 4 illustrates a flowchart of another method for density controlbased isolated hole growth, according to an aspect of the presentdisclosure;

FIG. 5 illustrates a flowchart for a scenario when holes are grown basedon density control, according to an aspect of the present disclosure;

FIG. 6 illustrates a method for percentage control based isolated holegrowth, according to an aspect of the present disclosure; and

FIG. 7 illustrates an exemplary plot showing different values forenabling pixels for hole growth in an output image, according to anaspect of the present disclosure.

DETAILED DESCRIPTION

As used in this disclosure, an “image” is a pattern of physical lightthat in digital image processing and xerographic applications isconverted to a two-dimensional array of data. Such data could bemulti-bit or binary. Alternatively, the image may be defined usingadditional dimensions for different planes or components of the image.For example, a monochrome image has one color plane and a color imagehas three or four color planes. Example embodiments disclosed hereinrelate to both monochrome as well as color images. An image may includecharacters, words, and text as well as other features such as graphics,including pictures. An image may be divided into “segments,” each ofwhich is itself an image. A segment of an image may be of any size up toand including the whole image.

An item of data can be used to define an image when the item of dataincludes sufficient information to produce the image. For example, atwo-dimensional array can define all or any part of an image, with eachitem of data in the array providing a value indicating the color of arespective location of the image. Likewise, one or more “scanlines” canbe used to define an image. A scanline divides an image into a sequenceof (typically horizontal) strips. A scanline can be further divided intodiscrete pixels for processing in a computer, xerographic, or printingsystem. This ordering of pixels by rows is known as raster order, orraster scan order.

Each location in an image may be called a “pixel.” In an array definingan image in which each item of data provides a value, each valueindicating the color of a location may be called a “pixel value”. Eachpixel value is a bit in a “binary form” of an image, a gray scale valuein a “gray scale form” of an image, or a set of color space coordinatesin a “color coordinate form” of an image, the binary form, gray scaleform, and color coordinate form each being a two-dimensional arraydefining an image. A “central pixel” is not literally the center pixelin a region, rather the term describes a target pixel in a scanlinebeing a single pixel or having a plurality of pixels. It will beappreciated that many or all of the pixels become the “central” or“target” pixel during the process of enhancing an entire image.Generally, the pixels make up individual features of the image. A binarypixel can take on two values: a 1 or 0.1 meaning ON and 0 meaning OFF.Specifically, one or more pixels that are ON and are contiguous or inclose vicinity of each other define one or more dots that are to beprinted by a printing device. Similarly, one or more pixels that are OFFand are contiguous or in close vicinity of each other define one or moreholes that are to be printed by a printing device. The illustratedaspects of this disclosure relate generally to a system, a method, and acomputer readable medium having stored thereon instructions forselectively processing isolated holes of an image to be printed by theprinting device. In some aspects of the disclosure, one or more pixelsmay make a hole, e.g., an isolated hole as described herein.

The term “ON state” of a pixel is defined with respect to the pixelhaving a binary logic level higher than that of a pixel with a lowerbinary logic level. For example, a pixel that is at a “1” level is in anON state as compared to a pixel at a ‘0’ binary level or an “OFF state.”The ON and OFF states of the pixels can be stored in a register in amemory device, although forms of physical storage may be used.

The term “data” refers herein to physical signals that indicate orinclude information. When an item of data can indicate one of a numberof possible alternatives, the item of data has one of a number of“values.” For example, a binary item of data, also referred to as a“bit,” has one of two values, interchangeably referred to as “1” and “0”or “ON” and “OFF” or “high” and “low.” An N-bit item of data has one of2^(N) values, where N is an integer value. A “multi-bit” item of data isan item of data or signal that includes more than one bits. The bits ofa binary number are ordered in sequence from Most Significant Bit (MSB)to Least Significant Bit (LSB) or vice versa. As used herein, “left” and“leftward” arbitrarily refer to a direction toward an MSB in sequencewhile “right” and “rightward” arbitrarily refer to a direction toward anLSB in sequence.

The term “data” includes data existing in any physical form, andincludes data that are transitory or are being stored or transmitted.For example, data could exist as electromagnetic or other transmittedsignals or as signals stored in electronic, magnetic, or other form.

An item of data relates to a part of an image, such as a pixel or alarger segment of the image, when the item of data has a relationship ofany kind to the part of the image. For example, the item of data coulddefine the part of the image, as a pixel value defines a pixel; the itemof data could be obtained from data defining the part of the image; theitem of data could indicate a location of the part of the image; or theitem of data could be part of a data array such that, when the dataarray is mapped onto the image, the item of data maps onto the part ofthe image.

An operation performs “image processing” when it operates on an item ofdata that relates to part of an image. A “neighborhood operation” is animage processing operation that uses data relating to one part of animage to obtain data relating to another part of an image.

Pixels are “neighbors” or “neighboring” within an image when there areno other pixels between them or if they meet an appropriate criterionfor neighboring. For example, using a connectivity criterion if thepixels are rectangular and appear in rows and columns, each pixel has atotal of 8 neighboring pixels contiguous with the pixel of interest.

Another criterion for defining a “neighborhood” includes selecting athreshold distance between two pixels that are enabled or in an ON statefor printing or display, as discussed below. Yet another criterionincludes counting a threshold number of pixels in an s×t windowsurrounding the pixel of interest, s and t each being integers.

Another criterion for defining a “neighborhood” includes selecting athreshold distance between two pixels that are enabled for printing as ahole or in an OFF state for printing or display, as discussed below.

An “image input device” is a device that can receive an image andprovide an item or items of data defining a version of the image. Adesktop “scanner” is an example of an image input device that receivesan image by a scanning operation, such as by scanning a document. Theresulting scanned document will have an input density of pixels.Scanning is carried out using, for example, a scanning bar in the mageinput device. The scanning bar scans the input image on a line by linebasis. The direction in which the scanning bar scans the image is termedas a “fast scan” direction at the beginning of each scanline of theimage. A second direction is termed as a “slow scan” direction thatcorresponds to a direction of movement of a printable medium (e.g.,sheet(s) of printing paper) storing the image. The adjectives “fast” and“slow” refer to relative speed of movement of the scan bar and theprintable medium.

An “image output device” is a device that can receive an item of datadefining an image and provide the image as output. A “display” and a“laser printer” are examples of image output devices that provide theoutput image in human viewable form, although any type of printingdevice known to one of ordinary skill in the art may be used. Theresulting output image will have an output density of pixels. Thevisible pattern presented by a display is a “displayed image” or simply“image” while the visual pattern rendered on a substrate by the printeris a “printed image”. The output image is printed using movement of oneor more components in the image output device.

“Circuitry” or a “circuit” is any physical arrangement of matter thatcan respond to a first signal at one location or time by providing asecond signal at another location or time. Circuitry specificallyincludes logic circuits existing as interconnected components,programmable logic arrays (PLAs) and application specific integratedcircuits (ASICs). Circuitry “stores” a first signal when it receives thefirst signal at one time and, in response, provides substantially thesame signal at another time. Circuitry “transfers” a first signal whenit receives the first signal at a first location and, in response,provides substantially the same signal at a second location.

“Memory circuitry” or “memory” is any circuitry that can store data, andmay include local and remote memory and input/output devices. Examplesinclude semiconductor ROMs, EPROMs, EEPROMs, RAMs, and storage mediumaccess devices with data storage media that they can access. A “memorycell” is memory circuitry that can store a single unit of data, such asa bit or other n-ary digit or an analog value.

“User input circuitry” or “user interface circuitry” is circuitry forproviding signals based on actions of a user. User input circuitry canreceive signals from one or more “user input devices” that providesignals based on actions of a user, such as a keyboard, a mouse, ajoystick, a touch screen, and so forth. The set of signals provided byuser input circuitry can therefore include data indicating mouseoperation, data indicating keyboard operation, and so forth. Signalsfrom user input circuitry may include a “request” for an operation, inwhich case a system may perform the requested operation in response.

For purposes of this disclosure, and not by way of limitation, an“isolated hole” is generally defined as a hole that satisfies one ormore criteria such as how close that hole is to the nearest pixel orgroup of pixels corresponding to another hole. Similarly, an isolatedhole may be defined as a hole that has a threshold number of holessurrounding that hole that are enabled for printing as a hole. Othercriteria for defining an isolated hole may be used too. The system maybe generically considered a printing system having an input image thatis processed for printing or displaying as an output image. The inputimage has an input density of holes with one or more pixels in an OFFstate, and an input density of dots with one or more pixels in an ONstate making up the input image. Correspondingly, the output image hasan output density or a desired density of holes and dots making up theoutput image. Typically, input and output densities are different sinceinput density of holes and dots is optimized for removing artifacts toresult in the output density of holes and dots, respectively.

“Hole growth” generally refers to a process in which a size of anisolated hole that does not meet a threshold size criterion suitable foroutputting is increased. For example, such increase in size may bereflected by selecting one or more pixels in a neighborhood of thedetected hole and disabling those pixels for outputting or printing.

Referring to FIG. 1, there is depicted a partly functional and partlyschematic diagram of an aspect of the present technology. An aspect ofthe present disclosure is employed as a system 100 for processing aninput digital image generated and/or provided by an ITT 106 to optimizegrowth of isolated holes therein. By way of example only, input imagecan be provided as a plurality of binary data signals representing, forexample, the text, halftone and graphic image regions that make up asource document from with the input image was generated, or is beinggenerated in real-time. That is, the input image may be produced as adigitized representation of a hardcopy document, for example, byscanning on a scanner. As illustrated in FIG. 1, the source of thedigital image (interchangeably referred to herein as “input image”) maybe any ITT, where the image is passed to or stored in memory 110.Alternatively, the term “input image” may be used to describe an imagethat is input to a hole growth system 114, described below. Memory 110may be suitable for the storage of the entire image or it may bedesigned to store only a portion of the image data (e.g., severalrasters or fast-scan lines). More specifically memory 110 stores datathat is representative of the imaging areas in the digital image. Memory110 can comprise computer readable media, namely computer readable orprocessor readable storage media, which are examples of machine-readablestorage media. Computer readable storage/machine-readable storage mediacan include volatile, nonvolatile, removable, and non removable mediaimplemented in any method or technology for storage of information,e.g., computer readable/machine-executable instructions, datastructures, program modules, or other data, which can be obtained and/orexecuted by one or more processors.

Memory 110 is a generic term and it may comprise a single memory or aplurality of separate memories. Such memories refer to computer readablemedia, and may be of the type that are removable from the camera, or ofthe type that are integrated into IIT 106 (e.g., a camera). Examples ofsuch memory may include, but are not limited to flash memory, USB thumbdrives, a memory stick, CDs, DVDs or other optical recording media,floppy disks or other magnetic recording media, or any other type ofmemory now known or later developed. Where memory 110 comprises a singlememory, the input image may be stored separately in memory 110.Likewise, the lower resolution images could be stored to a first memoryand the higher resolution images could be stored to a physicallyseparate second memory.

The data may be extracted from memory 110 on a raster basis or on apixel-by-pixel basis for use by the subsequent components or steps. Morespecifically, a pixel region window block 112 (referred to as window112) serves to select some or all pixels within a region of the image(accesses or extracts from memory 110), so as to make the data for therespective pixels available for processing. It will be appreciated thatwhile described as a static system, the disclosed embodiment is intendedto continuously operate on pixel data in a “streaming” fashion, and thatwindow 112 may be any suitable apparatus or methodology that allowsaccess to a plurality of pixels.

As described herein, window 112 determines different regions of thedigital image, the regions including a plurality of imaging areas. Suchregions are suitable for optimizing and controlling growth of isolatedholes therein. According to one aspect of the disclosure, such windowingmay include a plurality of fast-scan data buffers, wherein each buffercontains a plurality of registers or similar memory cells for thestorage of image data therein, with the data being clocked or otherwiseadvanced through the registers. The number of registers is dependentupon the “horizontal” (fast-scan) window size and/or line width, whereasthe number of buffers is dependent upon the “vertical” (slow-scan)window size. As will be appreciated, the window size is dependent upon acontext, as discussed in FIG. 2 below, that is required to implement theparticular image adjustment desired and the level of addressability ofthe imaging areas (higher levels of addressability will inherentlyresult in more data stored to provide the required context). While onewindowing technique has been generally described, it will be appreciatedthat similar means may be implemented using hardware and/or software topoint/access a memory device, so that data for selected imaging areasmay be accessed, rather than having the data separately stored in abuffer. It will also be appreciated that alternative configurations maybe employed for the buffer. For example, a single, long, buffer may beemployed, where image data is simply clocked through the buffer. Thusthe various alternatives all employ some form of memory for storingimage data representing image areas in at least one region of the image.

Output from window 112 is provided to hole growth system 114. Holegrowth system 114 includes one or more look-up tables (LUTs) 116, a holegrowth module 124 communicably coupled to a pseudo-random numbergenerator 122 (interchangeably referred to as a random number generator122) and a density control module 125 as shown by example connectingarrows, a processor 124, a local memory 126, and other logic circuitry(not shown). In one alternative aspect of this disclosure, LUTs 116 maybe a part of local memory 126. Hole growth system 114 carries outvarious functions and methods related to detection and growth ofisolated holes in an input image provided by ITT 106, and received byhole growth system 114 as a bitmap of pixels from window 112 andprovided to IOT 128 as an input for display and/or printing purposes.Hole growth module 124, random number generator 122, and density controlmodule 125 may be implemented using hardware (e.g., memory, registers,circuits). Alternatively, hole growth module 124, random numbergenerator 122, and density control module 125 may be software moduleswith code residing upon tangible computer readable medium to carry outvarious features and functions related to hole detection and growth.Further, hole growth module 124, random number generator 122, anddensity control module 125 may be a combination of hardware andsoftware, as may be contemplated by one of ordinary skill in the art. Byway of example only, and not by way of limitation, processor 124 can beconveniently implemented using one or more general purpose computersystems, microprocessors, digital signal processors, micro-controllers,application specific integrated circuits (ASIC), programmable logicdevices (PLD), field programmable logic devices (FPLD), fieldprogrammable gate arrays (FPGA) and the like, programmed according tothe teachings as described and illustrated herein, as will beappreciated by those skilled in the computer, software and networkingarts. For example, processor 124 can be a PENTIUM® processor provided byIntel Corporation, Santa Clara, Calif. Further, although a singleprocessor is illustrated, more than one processors coupled by a bus maybe used. Local memory 126 is similar to memory 110 and therefore,structure of local memory 126 is not being described in detail.

After processing at hole growth system 114 (e.g., using processor 124),input image transformed into an output image for printing and/ordisplaying at IOT 128. When displaying, IOT 28 comprises a display unit(not shown) for output image, although in alternative embodiments, IOT128 could also print the output image (e.g., when IOT 128 is at a printend of a copier). As will be appreciated, additional LUTs and storageand logic circuitry may be used for producing the output image at IOT128.

Referring to FIG. 2A, a context window 202 with respect to a fast scanand a slow scan direction is shown. Context window 202 includes a centerpixel or a target pixel 204, an inner row or ring of pixels 206, and anouter row or ring of pixels 208 surrounding or in the neighborhood ofcenter pixel 204. In one aspect, context window 202 is a part of aninput image that comprises a plurality of scanlines that are furthermade of a plurality of context windows, similar to context window 202.Pixels shown in context window 202 can be represented by at least onebinary value (“0” or “1”). A high binary value (e.g., “1”) indicatesthat the pixel is enabled for outputting (printing and/or displaying),and a low binary value (e.g., “0”) indicates that the pixel will not beprinted or displayed in an output image outputted by IOT 128. Therefore,context window 202 may be represented as a comprising a bitmap of binaryvalues stored, for example, in a register in memory 110. In the exampleshown in FIG. 2, inner ring 206 is a 3×3 pixel ring where pixels aredenoted as “N,” “S,” “E,” “W,” “NE,” “NW,” “SE,” and “SW” in terms oftheir location relative to center pixel 204. The pixels in the inner 3×3window are used to form an index to a programmable 256-entry 6-bit lookup table in look up tables 116 (e.g., LUT1). Such an index can bedefined as: index={NW, N, NE, W, E, SW, S, SE}, although other formatsfor defining the index may be used. For example, the order of pixelsforming the index may be changed. The look up table indexed by the indexis used for detection of center pixel 204 at beginning of each scanlineof the input image. For example, the MSB of the 6-bit detection look-uptable (“detectionLUT”) determines a region of the input image to whichcontext window 202 belongs. The remaining 5 bits of the 6-bitdetectionLUT are used to obtain one or more matching templates that willbe used to output image on IOT 128 and will form an output image contextwindow that may replace context window 202. For example, when a value ofthe remaining 5-bits is greater than 31, center pixel 204 is skipped andis not detected for hole growth of the hole in the input imagecorresponding to either a center pixel 204 or any of its adjacentneighboring pixels. In such a scenario, context window 202 will beunchanged in the output image. As will be appreciated by one of ordinaryskill in the art, additional criteria may be applied toward determiningwhether or not center pixel 204 will be detected for hole growth. Suchadditional criteria for inner ring 206 pixel values are disclosed inrelated U.S. patent application entitled “METHOD AND SYSTEM FOR ISOLATEDHOLE DETECTION AND GROWTH IN A DOCUMENT IMAGE,” Ser. No. 13/547,760,filed concurrently with the present application, the disclosure of whichis incorporated by reference herein in its entirety. An example of suchcriteria is described in FIG. 2B.

Referring to FIG. 2B, an exemplary set of patterns 200 may be used inisolated hole detection. For example, if the programmable hole growthfactor is set to four, then the pixels within the context window 202 arechecked against pixel patterns 210-272 of a third tier of patterns shownin FIG. 2B. That is, twenty five more patterns 222-272, or a total ofthirty one patterns 210-272 are checked if the hole growth factor is setto four.

All the pixel patterns 210-272 of the third tier have a hole growthfactor of four. The pixel patterns 210-272 of the third tier provide thecapability of growing a one-pixel hole, a two-pixels hole or athree-pixels hole to a four-pixels hole. For example, the pixel patterns210, 212, and 222 provide the capability of growing a one-pixel hole toa four-pixels hole. The pixel patterns 214-230 provide the capability ofgrowing two-pixels hole to four-pixels hole. The pixel patterns 232-268provide the capability of growing three-pixels hole to four-pixels hole.There will be no pixel hole growth when the programmable hole growthfactor is set to four and a four-pixels hole is present in the contextwindow. Additional examples of templates used for hole detection may befound in related U.S. patent application entitled “METHOD AND SYSTEM FORISOLATED HOLE DETECTION AND GROWTH IN A DOCUMENT IMAGE,” Ser. No.13/547,670), filed concurrently with the present application, thedisclosure of which is incorporated herein by reference in its entirety.

Referring back to FIG. 2A, in the example shown, the pixels from outerring 208 of the 5×5 window are arranged in a 16-bit array as {R0, R1,R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15}, althoughother numbers and/or other orderings of pixels may be used. In oneaspect of the disclosure, a number of “ON” pixels surrounding currentpixel 204 are counted using processor 124. The “ON” state pixelscorrespond to one or more dots in the input image that are alreadyenabled. Although the counting is carried out for outer ring 206 in 5×5context window 202, any window of size s×t within a neighborhood ofcurrent pixel 204 may be used, where s and t are integers. By way ofexample only, the 16-bit array may be stored in a register of memory110. This is to record the density of ON pixels in the neighborhood ofthe isolated hole i.e. the graylevel value surrounding the isolatedhole.

Various aspects of the present disclosure effectively deal with avariety of artifacts introduced in growth of holes in an image to beoutputted by IOT 128, and to better accommodate marking engines ofdifferent characteristics by using finer and more flexible control ofhole growth. Some examples of such artifacts include missing groups ofscanline in the output image, and lower than a desired density of dotsin each scanline of the output image outputted by IOT 128. As discussedwith respect to flowcharts 300-600 in FIGS. 3-6 below, the enabling ofhole growth in various regions of an image (e.g., highlights, known toone of ordinary skill in the art) is determined by using percentagecontrol of a number of pixels enabled for printing as a hole inconjunction with output density control of different regions of theimage based upon an input density of the input image obtained from IIT106. The image is subsequently stored in memory 110 as an n-dimensionalimage array, n being an integer greater than zero (0). Such a percentagecan either be a function of the number of holes not grown in theneighborhood of the current pixel, or it can be controlled using arandom number generator. In some aspects of the disclosure, thepercentage can be a function of both a random number and a number ofholes not grown. As can be appreciated, the output image at IOT 128 willhave hole density dependent upon the technique or the combination oftechniques used.

The various functions of the elements of system 100 may be controlled bya central microprocessor (e.g., processor 124), and the instructions tocarry out the exemplary methodology may be embedded in a chip, or may beloaded into a memory associated with the microprocessor as software.Such features and functions are illustrated and described with referenceto the flowcharts herein, and the steps in the flowcharts are by way ofexample only and not by way of limitation. For example, steps may beinterchanged, combined, or added to implement various features andfunctionalities of the technology in this disclosure. The particularmanner in which the elements of system 100 are controlled and the methodor process of the flowcharts is performed is not particularly critical,and other control structure or architecture may be used for system 100.

Referring to FIG. 3, an example process for density control of outputholes based upon the number of ON pixels in the neighborhood of detectedisolated holes in an input image is described using flowchart 300.

In block 302, processor 124 counts a number of pixels that are in an ONstate in a neighborhood of center pixel 204. For example, processor 124can count a number of ON pixels in outer ring 208 surrounding centerpixel 204. Alternatively, processor 124 can count a total number of ONpixels in an s×t neighborhood of center pixel 204, where s and t areintegers. The number determined from such counting is stored in localmemory 126 of hole growth system 114 as a variable (“ring16”). Thenumber of pixels in an ON state in the neighborhood of current pixel 204define an input density of the input image for each pixel of eachscanline making up the input image.

In block 304, processor 124 determines if current center pixel 204 wasdetected to be grown by a hole detection and growth algorithm. Forexample, processor 124 may check such detection using FIG. 2B, althoughany other form of hole detection and growth algorithm may be used. Ifyes, the flow proceeds to block 306. If no, the flow proceeds to block308.

In block 306, processor 124 determines if the value of ring16 variabledetermined in block 302 is greater than or equal to a programmableparameter or threshold value (“TH_SUM_ON”), the flow proceeds to block310. For example, value of ring16 may be based on pixels in a first ring(e.g., outer ring 208) or a second ring (e.g., inner ring 206), althoughother neighborhoods beyond such rings or rows may be used. If not, theflow proceeds to block 308.

In block 308, if processor 124 determines that center pixel 204 was notdetected as a pixel for hole growth, current center pixel is left as isin its current state. Such marking comprises updating registers andflags stored in local memory 126 indicating that center pixel 204 willnot be used for hole growth. In one example, processor 124 may revert tostep 302 for a next pixel after block 308.

In block 310, current center pixel 204 is used for hole growth byturning OFF a pixel value. Such enabling comprises marking pixelsneighboring center pixel 204 to an OFF state resulting in an enlargedhole comprising one or more pixels that may include center pixel 204 andadditional pixels surrounding center pixel 204 (e.g., one or morecontiguous or non-contiguous pixels from inner ring 206 and outer ring208). Corresponding updates may be made to registers and flags stored inlocal memory 126 indicating a growth of a hole corresponding to centerpixel 204.

Referring to FIG. 4, an example process for density control of outputholes based upon grown isolated holes in the neighborhood of the currentisolated hole (e.g., center pixel 202) in an input image is describedusing flowchart 400.

In block 402, at start of each scanline of the input image, processor124 sets an n-bit register in local memory 126 to zero, n being apositive integer value. For example, a register used for bit shiftingpurposes (“HoleBitShift”) may be set to all zeros. In one example, 8-bitregister HoleBitShift is used to keep track of the pixels turned OFF inthe fast scan direction, although other sizes of HoleBitShift registerin other scan directions may be used.

In block 404, processor 124 determines if current center pixel 204 wasdetected to be grown by a hole detection and growth algorithm. Forexample, processor 124 may check such detection using FIG. 2B, althoughany other form of hole detection and growth algorithm may be used. Ifyes, the flow proceeds to block 406. If not, the flow proceeds to block412.

In block 406, processor 124 determines if value of HoleBitShift registeris less than or equal to a programmable parameter(“LocalHoleDensity_TH1”). If yes, the flow proceeds to block 408, and ifno, the flow proceeds to block 412.

In one variation of the process shown by flowchart 400, after block 406,the flow proceeds to block 407 including blocks 407 a and 407 b. Inblock 407 a, when the condition in block 406 is satisfied, processor 124determines a sum of all ON bits in HoleBitShift register and stores thesum in a variable (“SumHoles”). In block 407 b, processor 124 determinesif this sum stored in variable SumHoles is less than or equal to thelocal density threshold variable “LocalHoleDensity_TH2”. If yes, theflow proceeds to block 412, and if not, the flow proceeds to block 408.

In block 408, current center pixel 204 is grown as a hole by turning OFFa pixel value. Such enabling comprises marking pixels neighboring centerpixel 204 to an OFF state resulting in an enlarged hole comprising oneor more pixels that may include center pixel 204 and additional pixelssurrounding center pixel 204 (e.g., one or more contiguous ornon-contiguous pixels from inner ring 206 and outer ring 208).Corresponding updates may be made to registers and flags stored in localmemory 126 indicating a growth of a hole corresponding to center pixel204.

In block 410, the HoleBitShift register is updated by right shifting abinary “1” into HoleBitShift register.

In block 412, when the hole is not to be grown, the HoleBitShiftregister is updated by right shifting a binary “0” into HoleBitShiftregister.

Referring to FIG. 5, an example process for density control of outputholes based upon density of grown holes in the current scanline, whichwould be the scanline of the current detected isolated hole in an inputimage is described using flowchart 500.

In block 502, at start of each scanline of the input image, a counter(“OnHoleCounter”) is set to zero. In one example, such a counter may bea 4 bit counter with binary values stored therein, although other typesof counters implemented using processor 124 and local memory 126 may beused.

In block 504, processor 124 determines if current center pixel 204 wasdetected to be grown by a hole detection and growth algorithm. Forexample, processor 124 may check such detection using FIG. 2B, althoughany other form of hole detection and growth algorithm may be used. Ifyes, the flow proceeds to block 510. If not, the flow proceeds to block506.

In block 506, center pixel 204 is not marked for growth and in block508, processor 124 leaves counter OnHoleCount in current state withoutaltering its contents.

In block 510, when center pixel 204 is determined to be selected forhole growth, processor 124 determines whether or not the value stored incounter OnHoleCount is less than or equal to an output density threshold(“OutputHoleDensity_TH”). In one example, OutputHoleDensity_TH may be a5-bit programmable register. If the counter value is less than thethreshold, the flow proceeds to block 512. If the counter value is notless than the threshold, the flow proceeds to block 516.

In block 512, current center pixel 204 is grown by turning OFF a pixelvalue. Such enabling for holegrowth comprises marking pixels neighboringcenter pixel 204 to an OFF state resulting in an enlarged holecomprising one or more pixels that may include center pixel 204 andadditional pixels surrounding center pixel 204 (e.g., one or morecontiguous or non-contiguous pixels from inner ring 206 and outer ring208). Corresponding updates may be made to registers and flags stored inlocal memory 126 indicating a growth of a hole corresponding to centerpixel 204.

In block 514, after current center pixel 204 is grown, processor 124increments counter OnHoleCount by one to indicate that current pixel 204was grown as a hole.

In block 516, when the condition in block 510 is not satisfied,processor 124 resets counter OnHoleCount to zero.

Flowchart 300 and 400 offer local density control for each pixel whereasflowchart 500 provides density control for a full scanline. Further,flowchart 300 checks the input density of the image whereas flowcharts400 and 500 look at the output density of the image. The methodologiesdisclosed in flowcharts 300-500 modify the desired output density basedon the input and/or output holegrowth density in some local or globalneighborhood of the current detected isolated hole to obtain an optimaloutput image for printing and/or display by IOT 128.

It is to be noted that the bit depths specified for the registersdescribed above are typical values and other values are possible. Bysetting the programmable thresholds accordingly, only flowchart 300 maybe carried out by processor 124, only flowchart 400 may be carried outby processor 124, or only flowchart 500 may be carried out by processor124. Further, processor 124 may carry out any combination of the threeadjustments of hole density illustrated by the processes of flowcharts300-600. Furthermore, although flowcharts 400 and 500 are carried out byprocessor 124 in the fast scan direction only to keep the implementationsimple, other variant implementations in other scan directions (e.g.,slow scan direction) may be additionally or optionally carried out byprocessor 124. The adjustments described by the processes of flowcharts300-500 can be invoked at different stages of hole growth.

FIG. 6 illustrates an example process for enabling hole growth invarious regions on the input image (e.g., in highlight regions) by usinga percentage control method described using flowchart 600.

In block 602, at start of each scanline of the input image,initialization of various counters and registers in memory 110 and/orlocal memory 126 is carried out. For example, a counter that counts anumber of pixels that were initially enabled for holegrowth based onsome isolated hole detection and growth algorithm but were laterdisabled for hole growth is initialized to a number “0” at start of eachscanline (“HolesNotGrown=0”). Likewise, location of a first center pixelor target pixel is recorded into a variable identifier“HolesNotGrownLocation” for which a binary holegrowth flag was initiallyset but is later reset to a binary “0” Likewise, a register (e.g., a“HoleShift” register) storing density control values is initialized tozero. Density control value is used to control the local density of theholes grown in some neighborhood of the current pixel (e.g., centerpixel 202).

In block 604, for each pixel in the scanline (e.g., current center pixel204), processor 124 determines whether or not the pixel is in an OFFstate, or is enabled for printing as a hole. For example, processor 124may determine whether or not a hole corresponding to the current pixelis to be grown. This may be indicated by setting a flag (e.g.,“HoleGrowthFlag=1”). If not, processor 124 in hole growth system 114goes to the next pixel, as indicated in block 606 and checks for thecondition in block 604 again for the next pixel. As noted earlier, oneor more pixels (e.g., center pixel 204) can correspond to one or moreholes in the input image. Holes in the input image determine an inputdensity of holes (and therefore, pixels) Likewise, the output image hasa corresponding output density of holes that is desired to overcome orremove the artifacts in the input image.

In block 608, processor 124 counts a number of pixels that are in an ONstate in a neighborhood of center pixel 204. For example, processor 124can count a number of ON pixels in outer ring 208 surrounding centerpixel 204 and store this number in a variable (“ring16”). Alternatively,processor 124 can count a total number of ON pixels in an s×tneighborhood of center pixel 204, where s and t are integers. The numberdetermined from such counting is stored in local memory 126 of holegrowth system 114. The number of pixels in an ON state in theneighborhood of current pixel 204 define an input density of the inputimage for each pixel of each scanline making up the input image. Thisnumber is then used to obtain values between −2″ to 2″ in a look-uptable discussed with respect to block 614 below. Upon determining thenumber of ON pixels, processor 124 carries out the processes of blocks610, 612, and 614 in parallel, although in some examples these processesmay be carried out in series.

In block 610, using random number generator 122, processor 124 generatesa random number. In one aspect of this disclosure, the generated randomnumber is in a finite range of −2^(m) to 2^(m), where m is an integer,although other ranges may be used. An exemplary value of m is 9,although other values may be used. It is to be noted that any techniqueof generating random numbers known to those of ordinary skill in the artcould be used, and the present disclosure is not limited to anyparticular technique of generating random numbers. For example, therandom number could be a “true” random number or a pseudo-random number,and may be generated by one or more computational techniques known toone of ordinary skill in the art implemented using processor 124.

In block 612, the value of ring16 from block 608 is used as an index toone or more LUTs 116 to output a hole density control value that is usedas a threshold against the density of grown holes in some neighborhoodof the current isolated hole (e.g., center pixel 202).

In block 614, the number of ON pixels counted in block 608 is used togenerate a percentage value for enabling a number of pixels for holegrowth in a plurality of pixels making up the scanline. Such percentagevalue may be obtained from a look-up table mapping values from thelook-up table (LUT) that maps values between values of “ring16” and−2^(n) to 2^(n) for percentage control. The output of the LUT which arethe percentage control values determine a percentage of enabled pixelsfor holegrowth out of a total number of enabled pixels for hole growthin the scanline that will be selectively enabled for hole growth by holegrowth system 114, and outputted by IOT 128. An exemplary table is shownas Table I below, although tables with other values may be developed:

TABLE I LUTs 116 Pixels in output Percentage ON state in Percentage ofPixels outer ring control enabled for hole 208 Values growth 16 −256 10015 −192 87.5 14 −128 75 13 −64 62.5 12 0 50 11 64 37.5 10 128 25  9 19212.5 0-8 256 0

For example, using the above table, if all pixels in the neighborhood ofthe current isolated hole detected and enabled for growth are in an ONstate, a 100% of these enabled pixels will be grown as holes based onthis criteria only, although additional criteria (as discussed below)may reduce the percentage value Likewise, if 10 pixels in outer ring 208are ON, then about 25% of pixels enabled for hole growth are selectivelyenabled in the output image outputted by IOT 128. As seen from Table Iabove, more than one (e.g., two or more) values for number of pixels inouter ring 208 that are in an ON state may correspond or map to the samepercentage value of pixels that are to be enabled for hole growth in theoutput image. Further, it is to be noted that the selected percentage ofpixels can be less than 100% indicating that not all pixelscorresponding to one or more isolated holes will be grown. The flowproceeds to block 618.

In block 616, processor 124 compares if a number of holes that wereenabled for hole growth based on some isolated hole detection and holegrowth algorithm but were not grown in a past context with respect tocurrent center pixel 204 is greater than or equal to a threshold number.If not, the flow proceeds to block 622. If yes, the flow proceeds toblock 618.

In block 618, processor 124 determines if location of current centerpixel 204 is less than or equal to a threshold distance from a locationof the last hole that was supposed to be grown based on some isolatedhole detection and growth algorithm but was not grown as discussed belowin blocks 642 and 646. Processor 124 may carry out this determination bycalculating an absolute value of the difference between a current centerpixel 204 and a “HolesNotGrown” variable initialized in block 602.Alternatively or additionally, processor 124 determine if the randomnumber generated in block 610 is greater than the percentage valueobtained from Table I above. If either of these conditions in block 618is true, the flow proceeds to block 620, else the flow proceeds to block622.

In block 620, processor 124 sets a hole density value equal to a holedensity control value obtained from block 612.

In block 622, processor 124 sets the hole density value equal to zero.Blocks 620 and 622 are used to perform density control for holes in twodifferent ways.

The flow from blocks 620 and 622 then proceeds to block 624.

In block 624, processor 124 counts a number of ON bits in the HoleShiftregister of block 602. This count may be stored in a variable“HoleCount” in local memory 126.

In block 626, processor 124 determines if the value of variableHoleCount is greater than the value of the variable HoleDensityVal ofblocks 620 and 622. If yes, the flow proceeds to block 634. If no, theflow proceeds to block 628.

In block 628, processor 124 sets the HolesNotGrownCounter to zero.

In block 630, processor 124 sets a least significant bit (LSB) ofHoleShift register to 1.

In block 632, processor 124 sets a HoleGrowthFlag to “1” indicating thata hole corresponding to the current pixel (e.g., center pixel 204) willbe grown as a hole. The flow then proceeds to block 646.

In block 646, the parameter HolesNotGrownLocation is set to 0,indicating for the future detected holes in that scanline that a holehas been grown in some pre-defined neighborhood of the current detectedhole. The flow then proceeds to block 606 via block 644 discussed below.

In block 634, processor 124 sets a least significant bit (LSB) ofHoleShift register to “0”.

In block 636, processor 124 sets a HoleGrowthFlag to “0” indicating thata hole corresponding to the current pixel (e.g., center pixel 204) willnot be grown as a hole.

In block 638, processor 124 increments HolesNotGrown counter. The flowthen proceeds to block 640.

In block 640, processor 124 determines if HolesNotGrownCounter is equalto “1”. If yes, it indicates that a pixel in the neighborhood of thecurrent detected hole is a first hole that was not grown as a hole andis detected as a result of any earlier hole growth logic previouslyapplied on the current pixel (e.g., center pixel 202). The flow proceedsto block 642. If no, it indicates that further initialization in thecurrent scanline is not needed and the flow goes to block 644.

In block 642, processor 124 sets a HoleNotGrownLocation variable tocurrent center pixel 204's location.

In block 644, processor 124 carries out a left shift operation in theHoleShift register by 1 bit. The flow then goes back to block 606.

The processes described in flowcharts 300-600 may be summarized in TableII below.

Table II illustrates an example with various parameters, variables, andconditions discussed above in flowcharts 300-600. For example, for TableII, for ring16=16, LUT 116 implies HoleDensityValue=2, and LUT 116HolePercentageVal=0 which means 50% of the pixels enabled for holegrowthbased on a hole growth algorithm (such as those known to one of ordinaryskill in the art) may be selectively enabled based on the examples ofhole growth algorithm in accordance with an embodiment. Similarly, forringNum=15, LUT 116 implies HoledensityValue=1, and LUT 116HolepercentageVal=68 means approximately 40% of the pixels enabled forholegrowth can be enabled for holegrowth based on examples of holegrowth algorithm in accordance with an embodiment.

TABLE II Registers/Variables Comments N N + 1 N + 2 N + 3 N + 4 N + 5N + 6 N + 7 1. HoleGrowth Hole is to be grown for 1 0 1 0 1 0 0 1 Flag :1/0 current center pixel 204 as (Block 604) dictated by a hole growthalgorithm 2. Rand_No Output of random number −199 61 −12 −110 204 180−256 −152 (Block 610) generator 122 3. Ring16 Number of ON pixels in(Block 608) neighborhood of current 16 16 16 16 16 16 16 16 pixel 204 4.HolesGrown Number of holes grown in 1 0 1 1 2 2 2 3 HoleShift registerThis is the HoleCount in block 624 from previous pixel 5.HoleNotGrownLocation 0 N N 0 0 0 0 0 (Blocks 642, 646 from previouspixel) 6. HolesNotgrownCounter 0 1 0 0 0 0 0 1 (Blocks 638, 628) againfrom previous pixel 7. Pixel enabled for Is 0 1 0 0 1 1 0 0 holegrowthbecause of Rand_No>=PercentageVal random number (Block 618) 8. Pixelenabled for Is abs(current_pixel- 0 1 1 0 0 0 0 0 holegrowth withHoleNotGrownLoca- HoleNotgrown logic tion)<=threshold_distance (Block618) 9. Holedensity Will be set to either a 1 or 0 X 2 X 2 X X 0 (Blocks620 and 622) 0 based on 7 and 8 above and block 616 HoleDensityvaluecomes from the LUT which will be either a 2/1 in this case. Holegrowthflag- Will be turned OFF if 0 0 1 0 1 0 0 0 updated value HolesGrown(Blocks 632, 636) >HoleDensity). HolesNotgrownCounter- Will be updatedbased on 1 1 0 0 0 0 0 1 updated value block 626. (Blocks 638, 628)Holes grown- New value of number of 0 0 1 1 2 2 2 2 updated value countsin HoleShift (Blocks 634, 630) register. Depending on whether it's LSBis set to a 1 or 0. HoleNotGrownLoc- New value based on block N N 0 0 00 0 N + 7 updated value 626 (Blocks 646, 642) Registers/Variables N + 8N + 9 N + 10 N + 11 N + 12 N + 13 N + 14 N + 15 1. HoleGrowth Flag : 1/00 1 0 0 1 0 1 0 (Block 604) 2. Rand_No 209 142 −185 −107 89 100 200 60(Block 610) 3. Ring16 (Block 608) 16 16 15 15 15 15 15 15 4. HolesGrown2 3 2 1 1 1 2 1 5. HoleNotGrownLocation N + 7 N + 7 N + 7 N + 7 N + 7 00 N + 14 (Blocks 642, 646 from previous pixel) 6. HolesNotgrownCounter 12 2 2 0 0 1 1 (Blocks 638, 628) again from previous pixel 7. Pixelenabled for holegrowth 1 1 0 0 1 1 1 0 because of random number (Block618) 8. Pixel enabled for holegrowth with 1 1 1 1 1 0 0 1 HoleNotgrownlogic (Block 618) 9. Holedensity X 2 X X 1 X 1 X (Blocks 620 and 622)Holegrowth flag-updated value 0 0 0 0 1 0 0 0 (Blocks 632, 636)HolesNotgrownCounter-updated value 1 2 2 2 0 0 1 1 (Blocks 638, 628)Holes grown-updated value 2 2 2 1 1 1 1 1 (Blocks 634, 630)HoleNotGrownLoc-updated value N + 7 N + 7 N + 7 N + 7 0 0 N + 14 N + 14(Blocks 646, 642)

For example, as shown in block 616, pixels N+7 and N+9 have an initialvalue of HoleGrowthFlag=1 coming from some prior art hole detectionalgorithm. For pixel N+7, random number generated is less thanHolepercentageVal (0 in this case for ring16=16) thus turning theHoleGrowthFlag OFF. For pixel N+9, random numbergenerated>HolepercentageVal but number of holes grown in HoleCount(Block626) is greater than the HoleDensityVal (which is 2 in this case-block612), thus turning the HolegrowthFlag OFF. Pixel N+12 satisfies theconditions for random number as well as the local hole density(HoleCount) and will be grown only if HolesNotgrownCounter (item 6 inTable II which is 2 coming from the previous pixel)>=threshold (e.g.,having a value of 1 in this example). Table II above shows that holesthat were supposed to be grown using some known holegrowth algorithm are7 out of a total of 16 in this example. (i.e., 7/16). Out of these 7pixels enabled for holegrowth, 3 were selectively enabled as a result ofHolesNotGrownCounter (3/16). Additionally, out of these 7 pixels enabledfor holegrowth, 4 were selectively enabled as a result of random numbergenerator (4/16) or (4/7), and out of these 7 pixels enabled forholegrowth, the total number of pixels selectively enabled were 5 (5/16)or (5/7). Thereafter, applying additional logic of hole density controldiscussed above, holes actually grown finally are three (3) in number,i.e., 3/7 or approximately 42.8% of total number of holes.

FIG. 7 illustrates a plot 700 showing flexible hole growth pattern basedon one or more conditions described above as a function of a number (n)of pixels surrounding center pixels 204 that are in an ON state.Generally, plot 700 shows a percentage of pixels enabled in the outputimage for hole growth. The output density is adjusted based upon one ormore methodologies illustrated in flowcharts 300-600 as discussed above.For example, line 702 in plot 700 shows percentage of pixels enabled forhole growth using random number generator 122 (e.g., in blocks 610-618).Line 704 illustrates further fine tuning by processor 124 to account fora number and distance of pixels that were enabled for hole growth basedon some known hole growth algorithm but were not grown in a past contextof context window 202, as discussed with respect to blocks 616 and 618in FIG. 6. Likewise, line 706 shows additional fine tuning using thehole density control value discussed in FIG. 3-6. As can be seen in plot700, depending on which technique or combination of techniques that arebeing used by processor 124 to adjust growth of isolated holes, aparticular percentage of pixels in each scanline of the output imagewill be enabled. For example, if 1-2 pixels surrounding center pixel 204are in an ON state in the input image, for the output image the numberof pixels enabled for holegrowth will be in a range centered around 50%of total number of pixels in the scanline in one case, by way of exampleonly and not by way of limitation. The range exists since processor 124adjusts the percentage of pixels depending on which methodology shown inFIGS. 3-6 is used. If only, a random number generator 122 is used byprocessor 124, then solid line (similar to line 702) closest to the 50%mark indicates the output hole density of the scanline. Likewise, ifonly holes not grown in a past context of center pixel 204 is utilizedby processor 124, then chained line (similar to line 704) indicates theoutput hole density of the scanline. However, since processor 124 mayutilize all or more than one methodology, each resulting in a differentoutput hole density, the final outputted scanline will have an outputdensity that could be a fine tuned or modulated average of the outputdensities obtained by the methodologies described in FIGS. 3-6. Further,it is to be noted that the ranges/margins of output percentage of pixelsenabled for hole growth is for example purposes only and is not meant tobe limiting.

The foregoing aspects of the disclosure have been provided as exampleswithin the scope of the technology disclosed and should not be regardedas limiting. To the contrary, the present disclosure is intended toencompass all modifications, substitutions, alterations, and equivalentswithin the spirit and scope of the following claims.

What is claimed is:
 1. A method for processing isolated holes of animage to be printed by a printer, comprising: generating at a processora random number lying in a finite range of numbers; determining at theprocessor whether a target pixel is to be turned off and enabled forprinting as a hole; determining at the processor a sum of pixelssurrounding a target pixel in a plurality of pixels in a scanline of theimage, the target pixel corresponding to an isolated hole in an inputimage, that are in an on state, the on state defined by a higher binarylogic level relative to a binary logic level corresponding to a turnedoff pixel; determining at the processor a numerical value stored in alookup table in a memory unit coupled to the processor using thedetermined number of pixels that are in the turned on state surroundingthe target pixel; comparing at the processor the generated random numberto the determined numerical value; and determining at the processorwhether the target pixel enabled for holegrowth is to be enabled forholegrowth based upon the comparing.
 2. The method of claim 1 furthercomprising: selectively enabling a percentage of pixels out of a totalnumber of pixels enabled for hole growth in the scanline surrounding thetarget pixel based upon the comparing; and printing the isolated holeincluding the target pixel as a result of the selective percentage ofpixels enabled for holegrowth as an output image on a printable mediumbased upon the comparison.
 3. The method of claim 2, wherein theselective enabling of a percentage of pixels enabled for holegrowthbased upon the comparing is carried out in an s×t pixel windowsurrounding each target pixel in the selected percentage of pixels, s, tbeing integers.
 4. The method of claim 2, wherein the enabling isfurther based upon a selected percentage of total number of pixels in ans×t window surrounding each pixel, s, t being integers.
 5. The method ofclaim 2, wherein the selective enabling comprises enabling based uponwhether a number of pixels enabled for holegrowth but not grown in apast scan of the printing is above a threshold number, such that theselected percentage is modified based upon the number of holes not grownin the past scan in an s×t pixel window of surrounding each pixel, s, tbeing integers.
 6. The method of claim 1, wherein the random number isan m-bit signed number, the finite range being −2^(m) to 2^(m), where mis an integer value.
 7. The method of claim 1, wherein the numericalvalue in the look-up table is generated by using the number of on pixelssurrounding the target pixel as an index value to the look-up table. 8.The method of claim 7, wherein at least two different values of thenumber of pixels map to a same numerical value in the look-up table. 9.The method of claim 1, wherein the selected percentage of pixels is lessthan 100% of the plurality of pixels in the scanline.
 10. A system forprocessing isolated holes of an image to be printed by a printer, thesystem comprising: one or more processors configured to: generate arandom number lying in a finite range of numbers; determine whether atarget pixel is to be turned off and enabled for printing as a hole;determine a sum of pixels surrounding a target pixel in a plurality ofpixels in a scanline of the image, the target pixel corresponding to anisolated hole in an input image, that are in an on state, the on statedefined by a higher binary logic level relative to a binary logic levelcorresponding to a turned off pixel; determine a numerical value storedin a lookup table in a memory unit coupled to the processor using thedetermined number of pixels that are in the turned on state surroundingthe target pixel; compare the generated random number to the determinednumerical value; and determine whether the target pixel enabled forholegrowth is to be enabled for holegrowth based upon the comparison.11. The system of claim 10, wherein the one or more processors arefurther configured to: selectively enable a percentage of pixels out ofa total number of pixels enabled for hole growth in the scanlinesurrounding the target pixel based upon the comparison; and print theisolated hole including the target pixel as a result of the selectivepercentage of pixels enabled for holegrowth as an output image on aprintable medium based upon the comparison.
 12. The system of claim 10,wherein the selective enabled percentage of pixels enabled forholegrowth based upon the comparison is carried out in an s×t pixelwindow surrounding each target pixel in the selected percentage ofpixels, s, t being integers.
 13. The system of claim 10, wherein thepixels are enabled further based upon a selected percentage of totalnumber of pixels in an s×t window surrounding each pixel, s, t beingintegers.
 14. The system of claim 10, wherein the selective enabledpixels comprise pixels enabled based upon whether a number of pixelsenabled for holegrowth but not grown in a past scan of printing is abovea threshold number, such that the selected percentage is modified basedupon the number of holes not grown in the past scan in an s×t pixelwindow of surrounding each pixel, s, t being integers.
 15. The system ofclaim 14, wherein the random number is an m-bit signed number, thefinite range being −2^(m) to 2^(m), where m is an integer value.
 16. Thesystem of claim 10, wherein the numerical value in the look-up table isgenerated by using the number of on pixels surrounding the target pixelas an index value to the look-up table.
 17. The system of claim 10,wherein the selected percentage of pixels is less than 100% of theplurality of pixels in the scanline.
 18. A tangible computer-readablestorage medium having one or more computer-readable instructions thereonfor processing isolated holes of an image to be printed by a printer,which when executed by one or more processors cause the one or moreprocessors to: generate a random number lying in a finite range ofnumbers; determine whether a target pixel is to be turned off andenabled for printing as a hole; determine a sum of pixels surrounding atarget pixel in a plurality of pixels in a scanline of the image, thetarget pixel corresponding to an isolated hole in an input image, thatare in an on state, the on state defined by a higher binary logic levelrelative to a binary logic level corresponding to a turned off pixel;determine a numerical value stored in a lookup table in a memory unitcoupled to the processor using the determined number of pixels that arein the turned on state surrounding the target pixel; compare thegenerated random number to the determined numerical value; and determinewhether the target pixel enabled for holegrowth is to be enabled forholegrowth based upon the comparison.
 19. The medium of claim 18,wherein the one or more processors are further configured to:selectively enable a percentage of pixels out of a total number ofpixels enabled for hole growth in the scanline surrounding the targetpixel based upon the comparison; and print the isolated hole includingthe target pixel as a result of the selective percentage of pixelsenabled for holegrowth as an output image on a printable medium basedupon the comparison.
 20. The medium of claim 18, wherein the selectiveenabled percentage of pixels enabled for holegrowth based upon thecomparison is carried out in an s×t pixel window surrounding each targetpixel in the selected percentage of pixels, s, t being integers.